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Studies from La Sapienza University yield new information about influenza
2009 AUG 4 - (NewsRx.com) -- According to recent research from Rome, Italy, "Previous reports have shown that various steps in the influenza A virus life cycle are impaired in cells expressing the antiapoptotic protein Bcl-2 (Bcl-2(+) cells). We demonstrated a direct link between Bcl-2 and the reduced nuclear export of viral ribonucleoprotein (vRNP) complexes in these cells." "However, despite its negative impact on viral replication, Bcl-2 did not prevent host cells from undergoing virally triggered apoptosis. The protein's reduced antiapoptotic capacity was related to phosphorylation of its threonine 56 and serine 87 residues by virally activated p38MAPK. In infected Bcl-2(+) cells, activated p38MAPK was found predominantly in the cytoplasm, colocalized with Bcl-2, and both Bcl-2 phosphorylation and virally induced apoptosis were diminished by specific inhibition of p38MAPK activity. In contrast, in Bcl-2-negative (Bcl-2(-)) cells, which are fully permissive to viral infection, p38MAPK activity was predominantly nuclear, and its inhibition decreased vRNP traffic, phosphorylation of viral nucleoprotein, and virus titers in cell supernatants, suggesting that this kinase also contributes to the regulation of vRNP export and viral replication. This could explain why in Bcl-2(+) cells, where p38MAPK is active in the cytoplasm, phosphorylating Bcl-2, influenza viral replication is substantially reduced, whereas apoptosis proceeds at rates similar to those observed in Bcl-2(+) cells," wrote L. Nencioni and colleagues, La Sapienza University. The researchers concluded: "Our findings suggest that the impact of p38MAPK on the influenza virus life cycle and the apoptotic response of host cells to infection depends on whether or not the cells express Bcl-2, highlighting the possibility that the pathological effects of the virus are partly determined by the cell type it targets." Nencioni and colleagues published their study in the Journal of Biological Chemistry (Bcl-2 Expression and p38MAPK Activity in Cells Infected with Influenza A Virus IMPACT ON VIRALLY INDUCED APOPTOSIS AND VIRAL REPLICATION. Journal of Biological Chemistry, 2009;284(23):16004-16015). For additional information, contact A.T. Palamara, Roma La Sapienza University, Dept. of Public Health Science, P le Aldo Moro 5, I-00185 Rome, Italy. Publisher contact information for the Journal of Biological Chemistry is: American Society Biochemistry Molecular Biology Inc., 9650 Rockville Pike, Bethesda, MD 20814-3996, USA. Keywords: Italy, Rome, Apoptosis, Biological Chemistry, Flu, Influenza, La Sapienza University. This article was prepared by Virus Weekly editors from staff and other reports. Copyright 2009, Virus Weekly via NewsRx.com.
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